DE102004061904A1 - Method for transmitting data packets - Google Patents

Abstract

The invention relates to a method for transmitting data packets in a radio system between a transmitter and a receiver, comprising the following steps:
a. Determining a desired transmit power for a data packet in response to a desired receive quality;
b. Transmitting the data packet with an actual transmission power;
c. Deriving a new target transmission power taking into account the actual transmission power used and the predetermined target transmission power, which is defined as a function of the reception quality intended for the transmission;
d. repeated transmission of the data packet with the new target transmission power.

Description

The The invention relates to a method for transmitting data packets in a radio system and a corresponding communication device, a Base station and the corresponding radio system.

For the future "Enhanced UMTS uplink "(E-DCH) becomes a packet-oriented transmission used with fast hybrid ARQ (HARQ), similar to that already for HSDPA standardized. In contrast to HSDPA however subject the "Enhanced UMTS uplink "the fast power control as described in Release 99. The too transmitting power of each channel (Release 99 and E-DCH) through so-called performance offsets to the DPCCH (Dedicated Physical Control channel, reference channel). The performance offsets are communicated to the mobile station by signaling ("higher layer signaling") or by a fixed method calculated from reference data. Thereby ensures that each channel on average the required target error rate reached.

If the mobile station as part of the fast power control their exceeds the maximum permitted transmission power, the transmission signal is scaled. Like the fast power control works this scaling on "slot basis" and changes the power ratios of the channels not to the reference channel.

in the Release 6 passes the send signal next to one or more DPDCH (s) (Dedicated Physical Data Channel) and a DPCCH (Dedicated Physical Control Channel) in addition one or more E-DPDCH (s) (Enhanced Dedicated Physical Data Channel). equivalent to then reduces the "slot-based" scaling in Release 6, the total transmit power at the terminal without the power ratios the individual channels to change the DPCCH. In picture 1 is the "Slot based "scaling shown. It takes place after the summation of the transmission signal instead of.

• • Skalierung nur des E DCH Kanals („E-DCH TTI basiert")
• • und Skalierung des E DCH und DCH Kanals („Slot basiert") Hauptgrund der Skalierung ist zu verhindern, dass die Mobilstation aufgrund der Nichtlinearität der Verstärker an der Sendeleistungsgrenze z.B. Datenübertragung in benachbarten Frequenzbändern stört. Mögliche Ursachen für eine Leistungsanforderung über der Sendeleistungsgrenze sind:
• • „Burstartiges" Auftreten einer Sendeüberschneidung von Kanälen mit Paketcharakteristik (z.B. gleichzeitiges Senden eines HSDPA ACK/NACKs und eines E-DCH Datenpakets)
• • Änderung der Datenrate eines oder mehrerer Transportkanäle insbesondere Änderung der Datenrate auf dem DCH Kanal
• • Schlechter werdende Kanaleigenschaften und dadurch höhere benötigte Sendeleistung

Since the service quality of the Release 99 DCH is prioritized in relation to the service quality of the E-DCH channel in Release 6, in addition to the "slot-based" scaling, an "E-DCH TTI-based" scaling is additionally provided, which at the beginning of the respective e-channel. DCH TTIs is performed. Thus, there are the following scaling methods in Release 6:

• • Scaling only the E DCH channel ("E-DCH TTI based")
• • and scaling of the E DCH and DCH channel ("slot based") The main reason for the scaling is to prevent the mobile station from interfering with data transmission in adjacent frequency bands due to the non-linearity of the amplifiers at the transmission power limit Possible causes for a power requirement above the transmission power limit are:
• • "Bursting" occurrence of a transmission overlap of channels with packet characteristics (eg simultaneous transmission of an HSDPA ACK / NACK and an E-DCH data packet)
• • Changing the data rate of one or more transport channels, in particular changing the data rate on the DCH channel
• • Deteriorating channel characteristics and thus higher required transmission power

As As described above, the E-DCH is a packet channel. In the case of power scaling becomes the transmitted Transmit a packet with less energy than the target energy, whereby the block error rate of this transmission compared to the Target block error rate increased.

Nice in UMTS Release 99 was specified that if a mobile station exceed their maximum transmission power threatens the performance of all channels scaled, i. evenly reduced becomes. In case that in Release 6 (E-DCH) a packet transfer due to the power limit of the mobile station, you use a 99 equivalent equivalent to the Release 99 - as described. additionally was for the E-DCH still the so-called "E-DCH only TTI based "scaling suggested which are similar how the R99 scaling works, but only here the E-DCH signal scales. When transmitting the E-DCH packets So far the disadvantage of the scaling and thus one opposite the Target block error rate increased block error rate be accepted. The missing energy of a transmission scaling does not work in the case of a retransmission considered and leads thus also in the retransmission an increase in the error rate.

Based on this prior art, it is an object of the invention, a way to Übertra supply, which ensures a high transmission quality with satisfactory transmission quality.

These Task is by the independent claims solved. Advantageous developments are the subject of the dependent claims.

For the transmission a data packet from a sender to a receiver becomes a target transmission power for this data package determined. This determination takes place depending on a reception quality with which the data packet at the receiver should be present.

A such desired transmission power is, for example, in particular for each transmission specified and is signaled for example by the receiver to the transmitter.

A transmission of the data packet takes place with an actual transmission power. These actual transmission power For example, due to specific conditions of the Target transmission power deviate.

A new target transmission power is taking into account the actually used Transmitted power and the predetermined target transmission power derived, then retransmit of the data packet.

This Method reduces interference and increases transmission capacity by: a new target transmission power taking into account already transmitted "energy" is done and not uses the default values specified.

Especially the method has advantages when a difference between actual Transmit power and target transmit power is determined and this difference to a predetermined target transmission power for the subsequent transmission is added.

A Adjustment of the transmission power can in particular only to feedback Recipient in terms of the reception quality respectively. Furthermore, this adjustment of the transmission power once in total for the transfer of the data packet. Alternatively, it is envisaged that the Adaptation for every time slot takes place. In this case, the transmission of the data packet takes place in a certain time interval, which is divided into time slots is.

The Target transmission power can depend on from the for the transfer intended reception quality be derived or from a central network element such as a Base station or generally the receiver can be specified.

The The invention further relates to a communication device for carrying out a Such method and a central network element, which in particular, can signal desired transmission powers, a reception quality of data packets can determine as well as feedback in terms of send this reception quality can and / or the behavior of the communication terminal according to this Considered invention (e.g., in deciding future resource allocations). Furthermore, the invention relates to a corresponding radio system.

Further Benefits are based on selected embodiments illustrated by figures, of which show:

1 : Representation of a HARQ operation where the transmitter is at the transmit power limit and an energy correction is used with a reduction in retransmission power and chase combining.

2 : A summation and scrambling of the transmission signal in the communication device or terminal, wherein a scaling after a common modulation several signals is made.

3 : A spreading and subsequent separate scaling of the E-DPCCH and the E-DPDCH

4 : A spreading and subsequent separate scaling of the DPCCH and the DPDCH

5 : A spreading and subsequent separate scaling of the DPCCH and the DPDCH

6 : An E-DCH sum signal, the transmitter transmitting at the transmission power limit via a so-called "Time Transmission Interval" TTI as a time interval.

In front a detailed consideration of the figures is only for the understanding and not restricting one Scope of the invention noted the following: For each transmitted Data packet is in particular a certain total energy or target energy required to get the data packet with a given probability to process correctly. This total energy can now by a one-time transfer with high transmission power or a multiple transmission with low transmission power respectively. In the former case, there is a slight delay until the predetermined probability is reached, however At the same time due to the high transmission power usually unwanted interference must be accepted. The fulfillment the "total energy condition" with only one transmission So only at high quality requirements, especially high requirements for a low delay, considering to be pulled. In the second case, lower interference results at the same time greater delay. The repeated transmission is therefore considered be pulled when the quality requirements are not that high. By optimizing the transmission power for the transmissions an optimal profile can be found, which gives the best possible Compromise between reception probability and delay as well represents the generated interference. In general, the requirements for different Services be different, so that the optimal transmission power both from the transferred Service as well as from the transmission (or transmission number, so first transmission, second, third ...) depends.

Furthermore, before a description of the figures, the environment in which the invention is applicable is described:
A transmission of data packets takes place in a radio system between a mobile station as transmitter and a base station as receiver.

at the radio system or communication network or communication system it is a structure for exchanging data. It can this is, for example, a cellular mobile network, such as the GSM network (GSM: Global System of Mobile Communications) or the UMTS network (UMTS: Universal Mobile Telecommunications System).

The Radio system includes at least two connection nodes, so it fall Also called point-to-point connections under this term. In a radio system, mobile stations are generally provided which have a Radio interface with each other. In UMTS points the radio system at least base stations, which here also Node B called radio network control units or radio Network Controller (RNC) for connecting the individual base stations on. The terrestrial radio access network or "Universal Terrestrial Radio Access Network" UTRAN is the radio-technical Part of a UMTS network, in which, for example, the radio interface to disposal is provided. A radio interface is always standardized and defined the entirety of physical and protocol specifications for the Data exchange, for example the modulation method, the bandwidth, the frequency deviation, access procedures, backup procedures or even Switching techniques. The UTRAN thus includes at least base stations as well as at least one RNC.

Basisstationene are - next to RNCs etc, as central entities in a communication network too understand in the case of a cellular mobile network mobile stations or communication devices within a cell, for example, the first cell or the second cell over one or more radio channels served. The base station puts the air interface in between Base station and mobile station, for which they have at least one transmission and / or receiving unit.

One Communication device, in particular a mobile station or terminal can be any communication terminal be over that a user communicates in a radio system FS. It's falling for example mobile radio terminals, like mobile phones or portable computers with a wireless module, including. In UMTS, a mobile station is often referred to as user equipment.

In mobile communications, a distinction is made between two connection directions. The Downlink ("DL") designates the transmission direction from the base station to the mobile station. The opposite direction, the uplink (UL), denotes the opposite transmission direction from the mobile station to the base station.

In Wideband transmission systems, such as a UMTS mobile network, a channel is a subset one available standing total transmission capacity, for example a frequency range. As a radio channel or channel is in the frame This application refers to a wireless communication path.

In A mobile radio system, for example UMTS, are for data transmission two types of channels provided: permanently assigned channels or "Dedicated Channels "and together used channels or "Common Channels". At the Dedicated Channels becomes a physical resource only for the transmission of information for one certain mobile station reserved. The common channels can transmit information be that for all terminals are thought, such as the primary common physical control channel PCCPCH in the downlink or all Mobile stations share this physical resource.

Of the E-DCH, about a mobile station UE is allowed to send data to the base station, if it receives a transmission permit from the base station be regarded as a kind of mixed form. The E-DCH is on the one hand a dedicated channel, since he has exactly one mobile station with one or more connects several base stations. On the other hand, from the base station, as in the case of a common channels granted a transfer license. This is necessary so that the signal level at the base station does not become so high that these are not the signals received from different mobile stations can properly decode.

in the The following will now be referred to the exemplary embodiments taken.

in the Trap that a packet transfer with scaled transmission power from the base station is confirmed negative (from the base station a NACK ("Not ACKnowledge") is transmitted to the mobile station), According to the invention, the repetition of the package with higher Transmit power (= energy) as the nominal power, at least if so due to new conditions during retransmission possible is. It has already been proposed retransmissions to send with lower energy than the first transmission, in this Case may well be possible be that in the retransmission no Transmission power limitation is present; but also a channel state change can cause in the repetition no more scaling is needed, yes that the packet energy even adjusted according to the scaling in the first transmission can. The goal is to ensure that the cumulative energy from scaled transmission and repetition at the receiver (= Base station) is equal to the total energy without scaling. The remaining residual error rate after receiving the repetition corresponds then the targeted target rate (The residual error rate after the second transmission is then as big as if at the first transmission no scaling would have taken place and the second transmission with the nominal power would have been sent).

Thus, according to the invention Ensures that the total energy from first transmission and retransmission at the receiver in the case of a scaling equal to the total energy without Scaling is. The remaining residual error rate after a packet transfer with scaling and "packet energy adjustment" according to NACK thus the residual error rate of a transmission as if no scaling had taken place.

In 1 is an illustration of a HARQ operation at the transmit power limit with energy correction using a HARQ with "Retransmission Power Reduction" and "Chase Combining".

Under a HARQ operation is a packet-oriented data transfer, in the correct or incorrect reception of a package with a corresponding confirmation, an "Acknowledge" or ACK if correct and an "emergency Acknowledge "resp. NACK is confirmed in case of incorrect reception. Continue to take place a forward error correction or FEC, which, for example, by a convolutional coding or turbo coding is realized.

"Retransmission Power Reduction" means that transmissions following the first transmission result in a reduction of the transmission power, which is due to the fact that for a correct decoding of a received data packet, this must be received by the receiver with a certain total energy more to provide the total transmit power when decoding is based on different received versions of the received data packet, the latter being called "chase combining". Of course, the invention is not on the example Chase Combining limited, but also for other methods applicable, for example, so-called "Incremental Redundancy" or "Full Incremental Redundancy".

In 1 is shown in the upper part 1, the packet transmission of a transmitter, in the event that no scaling is necessary. Here, the energy used for a transmission is shown as a rectangle.

in the middle part of the image in area 2 is the packet transmission of a transmitter represented by the transmission power limit must be scaled. The illustrated rectangles again correspond to energies.

in the lower part 3 is the energy 1EE in the soft buffer of the receiver for the case shown without scaling which of the energy 1ES of the first transmission of the data packet on the receiver side equivalent.

Farther the energy 2EE is shown in the soft buffer of the receiver, which contains the represents the proportion of energy 2ES received for the case with scaling.

you sees that due to the scaling the energy in the soft buffer Recipient after receiving the first transmission in case b) is lower than in case a).

According to one embodiment The invention is a power correction, whereby after the Repeat transfer the energy in the soft buffer of the receiver in case c) without original Scaling (case a) and in case d) with original scaling (case b) is the same and corresponds to the targeted energy.

in the Case c) here is a power control that senderseitig the energy 1ES is increased by d1ES, by at the first retransmission for the packet the energy is spent. Thus, the target energy becomes ototal achieved as the sum of d1EE and 1EE.

in the Case d) in the retransmission is that at the first transmission by scaling down energy ES to the energy d1ES for the retry data packet added. This results in a total of receiver side again the energy ETotal as the sum of 2EE, d1EE, EE.

• • Ausgleich der auf Grund von Skalierung fehlenden Energie in einer folgenden Wiederholung
• • Die Restfehlerrate, d.h. die Wahrscheinlichkeit dass ein Paket auch nach Empfang der Wiederholungsübertragung immer noch nicht korrekt empfangen werden kann, entspricht auch bei Skalierung der anvisierten Zielrestfehlerrate
• • Verhinderung eines Anstiegs von „Higher Layer Retransmissions" auf Grund der Leistungsskalierung. Higher Layer Retransmissions sind notwendig, wenn auch nach eine maximalen Anzahl von Wiedeholungsübertragung kein fehlerfreier Empfang möglich ist. Dann initiieren höhere Layer typischer Weise eine Wiederholung eines größeren Danteblocks, was wesentlich aufwändiger ist, als eine Wiederholung eines (Teil-) Paketes auf Layer 1 Ebene.
• • Reduzierung der auf Grund der Leistungsskalierung entstehenden Übertragungsverzögerung

The methods described above offer the following advantages for a data transmission method in the case of power scaling:

• • Compensate for the lack of energy due to scaling in a subsequent repetition
• • The residual error rate, ie the probability that a packet can still not be received correctly even after receiving the retransmission, also corresponds to the targeted target residual error rate when scaling
• • Preventing Higher Layer Retransmissions Increase Due to Power Scaling Higher-layer retransmissions are necessary, even if a maximum number of retransmissions fail to provide error-free reception, and higher levels typically initiate a repeat of a larger Dante block, which is significantly more costly is as a repetition of a (sub) package at Layer 1 level.
• • Reduction of the transmission delay due to power scaling

In 2 are explained in a UMTS system:

• A) Gemäß einer ersten Ausgestaltung erfolgt eine Skalierung S, die in diesem Falle Zeitschlitz basiert ist, sie erfolgt nach einer Aufsummierung und gemeinsamen Modulation.

2 shows the generation of the UMTS transmit signal in the terminal, as described in particular in the specification 25.213 v6.1.0 (version 6.1.0), in which the introduction of E-DCH for release 6 is described. The DPCCH, one or more DPDCHs, the HS-DPCCH and one or more E-DPDCHs will work as described in 2 shown summed up.

• A) According to a first embodiment, a scaling S, which is time slot based in this case, takes place after a summation and a common modulation.

In the 2 not shown in detail spread is for DCH, HS-DPCCH and E-DCH in 3 to 5 shown.

• B) Gemäß einer anderen Ausführungsform erfolgt eine Skalierung an der E-DCH-TTI Grenze („E-DCH TTI basierte" Skalierung), wobei eine Korrektur vorgenommen wird, was im folgenden ausgeführt wird:
• • Es liegen Daten mit einem bestimmten Transportformat vor.
• • Zum Sendezeitpunkt ist die benötigte Sendeleistung für das bereits vorliegende Transportformat höher als die maximal für den/die E-DPDCH(s) verfügbare Leistung im Terminal.
• • Anstelle der (aus signalisierten Referenz Werten) berechneten oder explizit signalisierten β_ed,k Werten, werden auf Grund der "TTI basierten" Skalierung reduzierte (niedrigere) β Werte β_ed,k,s z.B. während der Erst-Übertragung eines Pakets verwendet. Die Reduktion wird hierbei so gewählt, dass die Sendeleistungsgrenze bei Anwendung der reduzierten beta-Werte nicht überschritten wird.
• • Kommt es zu einer Wiederholungsübertragung wird die in der Erst-Übertragung zu wenig übertragene Energie berücksichtigt. Die entsprechend korrigierten β Werte für die Wiederholung β_ed,k,korr berechnen sich folgendermaßen (für die nur "E-DCH TTI basierte Skalierung" ist γ im folgenden gleich 1 zu setzen):
  
• • Berücksichtigt man auch bei weiteren Wiederholungsübertragungen die in den vorhergehenden Übertragungen auf Grund von Skalierungen fehlende Energie so ergibt sich für die n-te Übertragung = (n-1)-te Wiederholung (wir starten bei der Zählweise mit der 0-ten Übertragung als Anfangsübertragung) folgender korrigierter β Wert:
  
  
• • Dies kann auch iterativ dargestellt werden: βed,k,korr,0 2 = βed,k,0 2 βed,k,korr,1 2 = βed,k,1 2 + βed,k,korr,0 2 – γ0·βed,k,s,0 2 βed,k,korr,2 2 = βed,k,2 2 + βed,k,korr,1 2– γ1·βed,k,s,1 2 usw. βed,k,korr,n 2 = βed,k,n 2 + βed,k,korr,n-1 2 – γn-1·βed,k,s,n-1 2 Diese Formeln kann man folgendermaßen interpretieren: Als verwendete Sendeleistung wird die nominellen Sendeleistung verwendet, plus der Differenz aus der zuvor tatsächlich verwendeten Leistung und der zuvor vorgesehenen Leistung.
• • Eine weitere Ausführungsform ist es, die Wurzel in obiger iterativen Vorgehensweise mittels einer Reihenentwicklung zu nähern, oder sogar eine lineare Näherung zu verwenden, z.B.
  
  

In "slot-based" scaling, the power of the transmit signal S is scaled by a constant factor β, and the ratios of gain factors in the individual branches (β _hs , β _d , and β _{ed, k} to β _c ) change not according to a first embodiment, ie a Saklierung takes place only as in 2 shown after the common modulation.

• B) According to another embodiment, a scaling is performed on the E-DCH-TTI boundary ("E-DCH TTI based" scaling), with a correction made as follows:
• • There is data with a specific transport format.
• • At the time of transmission, the required transmission power for the transport format already present is higher than the maximum power available in the terminal for the E-DPDCH (s).
• • Instead of the β _{ed, k} values calculated (or signaled from signaled reference values) or reduced, β (reduced) β values β _{ed, k, s are used,} for example, during the first transmission of a packet due to the "TTI-based" scaling. The reduction is chosen so that the transmission power limit is not exceeded when using the reduced beta values.
• • If there is a retransmission, the energy transmitted in the initial transmission is not taken into account. The correspondingly corrected β values for the repetition β _{ed, k, cor are} calculated as follows (for the "E-DCH TTI based scaling" only, γ is to be equal to 1 in the following):
  
• • Taking into account the lack of energy in the previous transmissions due to scaling in further retransmissions, the result for the nth transmission is = (n-1) th repetition (we start with the count of the 0th transmission as the initial transmission ) the following corrected β value:
  
  
• • This can also be represented iteratively: β ed, k, corr, 0 2 = β ed, k, 0 2 β ed, k, corr, 1 2 = β ed, k, 1 2 + β ed, k, corr, 0 2 - γ 0 · β ed, k, s, 0 2 β ed, k, corr, 2 2 = β ed, k, 2 2 + β ed, k, corr, 1 2 - γ 1 · β ed, k, s, 1 2 etc. β ed, k, korr, n 2 = β ed, k, n 2 + β ed, k, korr, n-1 2 - γ n-1 · β ed, k, s, n-1 2 These formulas can be interpreted as follows: The transmission power used is the nominal transmission power plus the difference between the power actually used and the power previously provided.
• Another embodiment is to approximate the root in a serial iteration in the above iterative approach, or even to use a linear approximation, eg
  
  

• C) Gemäß einem weiteren Ausführungsbeispiel erfolgt eine Skalierung im TTI („slot-basierte" Skalierung) mit Korrektur, wie im Folgenden ausgeführt wird:
• • Innerhalb eines Übertragungsblockes (E-DCH TTI) wird in mindestens einem Slot die Leistungsgrenze der Mobilstation erreicht und „slot-basierte" Skalierung durchgeführt.
• • Bild 6 zeigt das Verhalten einer UE an der Sendeleistungsgrenze bei „slot-basierter" Skalierung. In Slot 11 wird auf Grund der Leistungskontrolle die E-DCH UE Sendeleistungsgrenze überschritten. Hervorgehoben gezeichnet ist der Sendeanteil der entsprechend skaliert wird, d.h. der Anteil der nicht gesendet wird. Streng genommen weiß die Mobilstation in einem solchen Fall nicht genau, mit wie viel Leistung sie zu wenig sendet, nur dass sie mit zu geringer Leistung sendet. Erfindungsgemäß wird die geforderte Leistung mit einer Schrittweite der Leistungsregelung abgeschätzt. Das ist meist eine konservative Abschätzung, d.h. i. a. wird die Leistung tatsächlich um einen größeren Anteil zu niedrig sein.
• • Ermittlung des Verhältnisses der an der Basisstation empfangene Paket-Energie mit Skalierung zur mindestens an der Basisstation empfangene Paket-Energie ohne Skalierung:
  

This series development brings particular advantages because the exact calculation of the root requires a very complex algorithm. However, the calculation of the beta values must be carried out very frequently, namely for each time slot. In addition, there is very little time available for the calculation since it can only be performed when the power control command has been received. Furthermore, it has to be considered that the beta values are only used in a quantized way and that the multiplications with these values have to be carried out even one or more times per chip (chip: duration after spreading). The loss of accuracy due to this discretization is generally greater than the loss of accuracy due to the approximation of the root function.

• C) According to a further embodiment, a scaling in the TTI ("slot-based" scaling) with correction takes place, as will be explained below:
• • Within a transmission block (E-DCH TTI), the power limit of the mobile station is reached in at least one slot and "slot-based" scaling is performed.
• • Figure 6 shows the behavior of an UE at the transmission power limit with "slot-based" scaling: Due to the power control, the E-DCH UE transmission power limit is exceeded in slot 11. The transmission proportion is highlighted, which is scaled accordingly Strictly speaking, in such a case, the mobile station does not know exactly how much power it sends out too little, only that it sends too little power.According to the invention, the required power is estimated with a step size of the power control, which is usually a conservative one Estimate, dhia, the performance will actually be too low by a larger proportion.
• Determination of the ratio of the scaled packet energy received at the base station to the packet energy received without scaling at least at the base station:
  

N

Anzahl der Zeitschlitze die skaliert werden

α

Schrittweite der schnellen Leistungsregelung (linear, d.h. die Leistung nach Anwendung eines Schrittes zur Erhöhung der Leistung verhält sich zur Leistung vor dem Schritt wie 1: α, also ist α > 1. Bei den übliche 1dB Schritten ist α= 1,26.

N_TTI

Anzahl der Zeitschlitze eines E-DCH TTIs

K

Korrekturfaktor

• • Ausgleich der Energie in der Wiederholungsübertragung durch Korrektur der β Werte entsprechend wie in B) beschrieben, allerdings mit dem hier berechneten γ Faktor und β_ed,k,s,i = β_ed,k,i. Dabei bezieht sich γ₀ auf die in der Anfangsübertragung durchgefürte "slot-basierte" Skalierung und γ₁ auf die in der ersten Wiederholungsübertragung durchgeführte "slot-basierte" Skalierung usw.
• D) Gemäß einem anderen Ausführungsbeispiel erfolgt sowohl eine Skalierung an der TTI Grenze („E-DCH TTI basierte" Skalierung) als auch im TTI („slot-basierte" Skalierung) mit Korrektur:
• • Dieses Ausführungsbeispiel kombiniert die Berücksichtigung der beiden Skalierungen, es ist also eine Kombination der beiden vorigen Ausführungsbeispiele.
• • Es liegen Daten mit einem bestimmten Transportformat vor (d.h. Anzahl der Daten im Übertragungsblock liegt vor), zum Sendezeitpunkt ist die benötigte Sendeleistung höher als die maximal verfügbare E-DPDCH Leistung
• • Zusätzlich wird innerhalb eines Übertragungsblockes (E-DCH TTI) in mindestens einem Slot die Leistungsgrenze der Mobilstation erreicht und „slot-basierte" Skalierung durchgeführt
• • Ausgleich der Energie wie in B) beschrieben und mit den γ Faktoren wie in C) beschrieben.
• E) Gemäß einem weiteren Ausführungsbeispiel erfolgt eine Begrenzung der Skalierung auf Maximalwerte
• • Insbesondere in dem Fall, dass mehrere Übertragungen, also z.B. Erstübertragung und eine oder mehrere Wiederholungsübertragungen skaliert werden müssen kann es sein, dass durch Berücksichtigung der zurückliegenden Skalierungen für die aktuelle Übertragung der β Wert verhältnismäßig stark erhöht wird, z.B. um mehr als 3dB. Zwar ist auch dann eine so hohe Erhöhung prinzipiell notwendig, um die nominelle Fehlerrate zu erreichen, allerdings bringt eine Aussendung mit recht hoher Leistung auch Nachteile: Sie erzeugt erhöhte Interferenz für andere Übertragungen, die dort vielleicht zusätzlich auch nicht vorhergesehen wurden. Des Weiteren wird die Übertragungsenergie dann auch meist zu groß sein in dem Sinn dass in einem großen Teil der Fälle auch eine deutlich geringere Energie für eine erfolgreiche Übertragung ausgereicht hätte. Der überschießende Teil der Energie wurde dann nutzlos verwendet.
• • In diesem Fall kann man vorsehen, dass die Leistung bzw. die β Werte maximal um einen gewissen Betrag (bzw. einen maximalen Faktor) gegenüber den nominellen Werten erhöht werden. Der verwendete β Wert errechnet sich also aus dem Maximum aus diesem Maximalwert und dem nach einem vorstehenden Ausführungsbeispiel berechneten Wert.
• • Hinweis: Insbesondere in diesem Fall wird sich der Fehler durch die Näherung der Wurzel nicht stark bemerkbar machen, da in diesem Fall die Abweichung vom nominellen β Wert recht klein sein wird, und die Näherung
  
  für kleine x nur einen kleinen Fehler aufweist.

Since the packet energy received at the base station can only be estimated without scaling, it is also possible to take this into account in the γ factor by means of the correction factor K:

N

Number of time slots that are scaled

α

Increment of the fast power control (linear, ie the power after applying a step to increase the power behaves to the power before the step like 1: α, so α> 1. In the usual 1dB steps, α = 1.26.

N _TTI

Number of time slots of an E-DCH TTI

K

correction factor

• • compensation of the energy in the repetition transmission by correction of the β values corresponding to that described in B), but with the γ factor calculated here and β _{ed, k, s, i} = β _{ed, k, i} . Here, γ ₀ refers to the "slot-based" scaling performed in the initial transmission, and γ ₁ refers to the "slot-based" scaling performed in the first retransmission, and so on.
• D) According to another embodiment, both a scaling at the TTI limit ( " E-DCH TTI based "scaling) as well as in TTI (" slot based "scaling) with correction:
• This embodiment combines the consideration of the two scalings, so it is a combination of the two previous embodiments.
• • There is data with a certain transport format (ie number of data in the transmission block), at the time of transmission the required transmission power is higher than the maximum available E-DPDCH power
• • In addition, within a transmission block (E-DCH TTI) in at least one slot, the power limit of the mobile station is reached and carried out "slot-based" scaling
• • Compensation of energy as described in B) and with the γ factors as described in C).
• E) According to a further embodiment, the scaling is limited to maximum values
• In particular, in the case that several transmissions, ie first transmission and one or more retransmissions must be scaled, it may be that by taking into account the past scaling for the current transmission of the β value is increased relatively high, for example by more than 3dB. Although such a high increase is in principle necessary to achieve the nominal error rate, but a transmission with quite high power also brings disadvantages: It produces increased interference for other transmissions, which might also have not been foreseen there. Furthermore, the transmission energy will then usually be too large in the sense that in a large part of the cases a significantly lower energy would have sufficed for a successful transmission. The surplus part of the energy was then used uselessly.
• • In this case, it can be provided that the power or the β values are maximally increased by a certain amount (or a maximum factor) compared to the nominal values. The β value used is thus calculated from the maximum of this maximum value and the calculated value according to a preceding embodiment.
• • Note: Especially in this case the error will not be noticeable by the approximation of the root, because in this case the deviation from the nominal β value will be quite small, and the approximation
  
  for small x has only a small error.

Farther the following should be noted: mobile stations are not only subject restrictions in terms of the maximum transmission power, but also with respect to the minimum transmission power. i.e. that the mobile station always with a certain minimum power even if the base station signals that the Performance should be reduced. The reason is that elements of signal generation not cost-effective can be built with any dynamics. For example, the Dynamics of a digital-to-analog converter limited. In this case will also made a scaling of the overall signal, just natural too the (then higher) Minimum performance. In the foregoing, in the examples, the embodiments always assumed that too little energy was spent. Naturally You can use the formulas and procedures even if too a lot of energy was spent.

In a further preferred embodiment But a distinction is made, whether too much or too little Energy was expended. If too little energy was expended, the correction is performed as described. But was too much energy Expenses, the correction is not performed, or only mitigated. This In itself at first glance nonsensical suggestion can be as justification: True was e.g. in the first transmission sent with too much energy, on the other hand, the question arises the energy for the retransmission only if the previous transfer not be carried out successfully could. In this case, then even the high energy was not sufficient to transfer the package correctly. It is not meaningful, the retransmission to equip with too little energy. This becomes particularly clear if you look at a special case: it may be that in the first transmission already spent so much energy, as in itself for first transmission and the next transmission was provided. In that case, would when applying the correction so the retransmission send with energy 0, which of course is nonsensical. In this case, there should be no reduction in the transmission power / energy to 0, but it should be with a certain minimum performance be sent. Advantageously, therefore, a method similar to the apply the method of limitation of correction shown above, only that here is a limitation of the correction to a certain minimum is applicable. That you choose the transmission power as a maximum of a predetermined minimum power and the under consideration the excessive power transmitted in the previous transmission reduced power.

Claims (13)

Method for transmitting data packets in a radio system, between a transmitter and a receiver, with following steps: a. Determining a target transmission power for a Data packet depending from a desired one Reception quality; b. Transfer of the data packet with an actual Transmission power; c. Derive a new target transmit power under consideration the actual spent transmission power and the target transmission power; d. Repeated transfer of the data packet with the new target transmission power. The method of claim 1, wherein for the derivation in step c), the difference between desired transmission power and actual Transmission power for at least one previous transmission is determined and adds this difference to the desired transmission power becomes. Method according to Claim 1 or 2, in which the data packet while a time interval is transmitted, which is divided into several time slots and the receiver of the Data packets to the sender for each time slot transmits a power control feedback indicating whether a power control of the transmission power should take place and the new target transmission power in step c) for a subsequent time slot below consideration the actual used transmission power for the data portion is derived in the timeslot. Method according to one of the preceding claims, in for every data packet for every transmission a reception quality for the Reception at the receiver is provided and the predetermined target transmission power for the subsequent transmission in step d) depending from the for the transfer intended reception quality is defined. Method according to one of the preceding claims, in the maximum transmission power during the transmission of a data packet is predetermined and a deviation of the actual transmission power of the desired transmission power by exceeding the maximum Transmission power is conditional. A method according to claim 5, wherein for deriving in step c) it is assumed that in time slots in which the Power control does not exceed the maximum Transmission power leads the actual Transmit power equal to the target transmit power is selected and assumed that in time slots where the power control is overshooting the maximum transmit power would the actual Transmission power by a certain ratio less than the target transmission power is. Method according to the preceding claim 6, at the power control takes place in specified increments and the specific ratio corresponds to a power control step size. Method in which provided several data transmission channels are whose data is transmitted in common data packets and a target transmission power after a common modulation of the data in the data packets is set. Method in which provided several data transmission channels are whose data is transmitted in common data packets and a target transmission power before a merge the individual data transmission channels takes place. Method according to one of the preceding claims, in in d) repeated transmission on request. Communication device with a transmitting / receiving unit for sending and / or receiving data and with a processor unit, which to perform following steps is set up: a. Determining a target transmission power for a Data packet depending from one of the desired Reception quality; b. Transfer of the data packet with an actual Transmission power; c. Derive a new target transmit power under consideration the actual used transmission power and the predetermined target transmission power, which depending from the for the transfer intended reception quality is defined; d. Repeated transmission of the data packet with the new nominal transmission power. Central network element, in particular base station with a transceiver for transmitting and / or receiving Data and a processor unit, which for performing the following Steps is set up. a. Receiving data packets; b. Examining data packets for their reception quality; c. To transfer a feedback in terms of the reception quality to a sender of the data packet. Radio system with at least one communication device according to claim 11 and a central network element according to claim 12.